compression 11hp b&s

[whitt]

wondering what the compression on a 11hp b&s is suppose to be? It is a john deere riding mower but doesn't have much power when you run the mower.

thanks

[Ulysses]

I'm not sure about the bigger ones but on the small engines (3-5 HP) they don't give a specific compression--if the compression is enough to blow your thumb out of the spark plug hole then it's enough to run the engine. Pretty sophicated huh?

[ds549]

60-80lbs one will run. 100-125 is very good.

[Duane Bozarth]

In general you can figure a compression ratio of from 7 to 9 for a gasoline engine which is roughly 100 - 135 psi. For small engines the lower end is more typical. As someone else I think noted, they'll run down to about 60-80 psi, obviously losing power as there's lower compression.